Price
CaptainsGround
Free during early access
Mariners Learning System
~$549 OUPV course
CaptainsGround vs Mariners Learning System
Mariners Learning System is a long-standing online prep provider with USCG-approved exam authority. CaptainsGround is free, citation-backed, and built around adaptive drilling — different value props for different candidates.
TL;DR
MLS: paid course (~$549), USCG exam authority included, video lectures. CaptainsGround: free, citation-linked drills + lessons + FSRS flashcards + mock exams, no exam authority — you take the test at a REC.
USCG exam authority
CaptainsGround
No (you test at a REC)
Mariners Learning System
Yes (test at home)
Citation links
CaptainsGround
Every Q linked to source
Mariners Learning System
Limited
Drill question count
CaptainsGround
500+ approved
Mariners Learning System
Module-style banks
FSRS spaced repetition
CaptainsGround
Yes (FSRS-4)
Mariners Learning System
No
Mock exam
CaptainsGround
70Q × 90min, NMC format
Mariners Learning System
Yes
Study format
CaptainsGround
Read + drill + flashcards
Mariners Learning System
Video + reading + Q-bank
Bottom line
If you want to test at home and don't mind paying, MLS is the convenient package. If you'll test at a REC anyway and want a free, citation-backed prep tool, CaptainsGround is the better fit.